The present invention relates to a cost effective and environmentally acceptable method for removal of hydrogen sulfide (H.sub.2 S) from so-called "sour gas".
Reduction or elimination of undesirable by-products associated with source materials such as refinery, natural gas and geothermal energy sources, have been generally treated as an expenditure in the context of the overall operation and a technical problem for the pollution control engineer. Hydrogen sulfide, the particular pollutant addressed by the method of the present invention usually has relatively little commercial value and often represents a secondary disposal problem after removal from a primary process stream. While release of low level H.sub.2 S emissions into the atmosphere have been acceptable in the past, many modern governmental pollution control agencies continue to adopt more stringent standards, making further H.sub.2 S abatement mandatory.
Many conventional hydrogen sulfide abatement processes pose secondary or technical problems which make the abatement process both costly and difficult to maintain in operation.
One such conventional abatement scheme known as the "Stretford" process is used to treat non-condensable off-gas streams. The Stretford process uses an alkaline scrubbing solution generally containing a vanadium catalyst so that hydrogen sulfide is both absorbed into a scrubbing solution and also oxidized to form sulfur in an oxidation-reduction reaction involving the vanadium component of the scrubbing solution. Although the "Stretford" process is extremely efficient in the removal of H.sub.2 S from off-gas, the process is relatively costly and complex in nature, requiring various chemical solutions to be introduced in the process stream and frequent monitoring for proper operation by technical personnel.
Accordingly, those skilled in the art concerned with hydrogen sulfide removal and abatament from sour gas streams have recognized a significant need for reducing H.sub.2 S content to an acceptable level without costly expenditure.